Internal peening tool

ABSTRACT

An impact tool for peening the interior wall of a bore, wherein a sleeve has rows of axially staggered holes through which peening arms project, the arms being carried by a central rod reciprocable in the sleeve and spring biased in a direction to retract the arms, impact being applied to the rod and acting to project the arms through the holes into engagement with a bore wall. The sleeve has a collar for limiting the extent of insertion of the tool into a bore, and a handle is provided to enable rotation of the tool in the bore. The rod engages an adjustable anvil to limit the extension of the peening arms from the sleeve.

United States Patent Gardner 51 Mar. 14, 1972 [54] INTERNAL PEENING TOOL21 Appl. No.: 846,716

[52] US. Cl ..72/399 [51] 1nt.Cl. ..B21d 41/011,821] 7/16 [56]References Cited UNITED STATES PATENTS FORlElGN PATENTS OR APPLlCATlONS1,023,564 3/1966 Great Britain ..72/393 Primary Examiner-Charles W.Lanham Assistant Examiner-E. M. Combs Attorney-Bernard Kriegel [57]ABSTRACT An impact tool for peening the interior wall of a bore, whereina sleeve has rows of axially staggered holes through which peening armsproject, the arms being carried by a central rod reciprocable in thesleeve and spring biased in a direction to retract the arms, impactbeing applied to the rod and acting to project the arms through theholes into engagement with a bore wall. The sleeve has a collar forlimiting the extent of insertion of the tool into a bore, and a handleis provided to enable rotation of the tool in the bore. The rod engagesan adjustable anvil to limit the extension of the peening arms from thesleeve.

10 Claims, 3 Drawing Figures a 0 W? a Q. m 5 E .ll. 0 O 0 O o 2 w W AWW5. A/N Omen/v52 INTERNAL PEENIING TOOL In the manufacture of variousdevices or machinery it is the practice to shot peen or otherwisemechanically work certain materials to produce a hardened surface. Theworking or shot peening of external surfaces is a relatively simpleoperation, but it is also desirable that the walls of bores be workhardened or shot peened, and such operations are not easilyaccomplished. In the usual shot peening process, there is no assurancethat the cylindrical wall of a bore will be uniformly worked.

The present invention involves the provision of an efficient tool,whereby the interior cylindrical wall of a bore in work hardenablematerial, or other material, may be uniformly peened in a simple manner.

More particularly, the present invention provides a tool having a bodyor sleeve adapted to be disposed in a bore or cylindrical hole in aworkpiece, the sleeve having peening arms or elements which are radiallyand forcibly extensible into impact engagement with the bore wall, so asto effectively peen the entire bore wall surface that is to be workhardened.

In accomplishing the foregoing, an object of the invention is theprovision of a rugged tool adapted for ease of utilization. In thisconnection, the sleeve may be rotated to move the peening elements todifferent locations in the bore, the extent or depth of the peeningaction being adjustable.

This invention possesses many other advantages, and has other purposeswhich may be made more clearly apparent from a consideration of a formin which it may be embodied. This form is shown in the drawingsaccompanying and forming part of the present specification. It will nowbe described in detail, for the purpose of illustrating the generalprinciples of the invention; but it is to be understood that suchdetailed description is not to be taken in a limiting sense.

Referring to the drawings:

FIG. 1 is an isometric view of a peening tool made in accordance withthe invention;

FIG. 2 is a vertical section showing the peening tool disposed in thebore of a workpiece, with the peening elements expanded; and

FIG. 3 is an enlarged horizontal section taken on the line 3-3 of FIG.2.

As seen in the drawings, the peening tool of the present inventioncomprises a hollow support or body in the form of a tubular sleeve.Reciprocable in the body 10 is a central rod 11 carrying a number ofrows of circumferentially spaced peening elements or arms 12 whichextend through side openings 13 in the cylindrical body 10. Thus, whenthe body 10 is disposed in a bore hole 14 of a workpiece l5, impactforces may be applied to the center rod 11 to force the peening arms orelements 12 outwardly into forceful engagement with the bore wall 14 towork the same.

More specifically, the cylindrical body 10 is of a desired length for arange of bore depths, and the body 10 is of a desired diameter for arange of bore diameters. At its upper end, the body 10 has a closure cap16 suitably connected or affixed thereto. To limit the extent of entryof the body 10 into a bore of a workpiece, the body has an abutmentflange 17 secured to it, adjacent to its upper end and adapted to engagethe transverse surface 18 of the workpiece 15.

The openings 13 are arranged in vertical rows, in the illustratedembodiment, and the openings of the adjacent rows are in spiralrelation. This is to say, the openings of adjacent rows arecircumferentially spaced and axially staggered so as to overlapslightly. A handle 19 is suitably attached, as by a weld 20, to theupper end of the body 10, whereby the body may be rotated in use, aswill be hereinafter described, to enable effective working of the entiresurface ofthe bore wall 14.

At its lower or inner end, the body 10 has a reduced diameter threadedportion 21 on which is threadedly engaged the side wall 22 of an end cap23. The end cap 23 has a central anvil 24 in the form of a cylindricalpost around which is disposed a coil compression spring 25 seating onthe end cap 23. At its other end, the spring 25 is disposed about areduced diameter end portion 26 of the center rod 11 and seats against adownwardly facing shoulder 27 on the rod 11. The spring 25 thus providesa force tending to move the center rod upwardly, in a direction toretract the peening arms or elements 12. The upper end of the center rodIII. has a reduced diameter portion 28 extending through an opening 29in the top closure 16, the rod 11 providing an upwardly facing shoulder30 engageable with the cap 16 to limit its upward movement in the body10.

The peening elements or arms 12 are mounted on the center rod 11 bysegmental clamping collars, each segment 31 of which has outstandingcars 32. The inner end of each peening element or arm 12 is pivotallyconnected between a pair of adjacent cars 32 by a pivot pin 33 suitablyfixed to the ears. Preferably, the clamp segments are internallygrooved, as seen at 34 in FIG. 3, to receive a circumferentiallyextending rib 35 on the center rod 11, whereby to prevent axial shiftingof the collar segments on the rod 11.

At their outer ends, the peening arms or elements 12 extend through theopenings 13 and are case hardened, as indicated at 36, or otherwisesuitably hardened, to resist wear as a result of repeated impact withthe cylindrical wall 14 which is to be hardened. In addition, each ofthe ends 36 has its end surface formed on an arc, as indicated at 37, oris otherwise conversely curved, whereby the arm ends 36 contact the borewall 14 over a relatively short segment of the arcuate end surface 37,but the arms 12 are effective over a range of relative bore sizes.

In the use of the peening tool described above, the body 10 is insertedinto the bore 14, with the peening arms or elements 12 retracted underthe influence of the spring 25, as limited by engagement of the shoulder30 on the rod 11 with the top plate 16. Insertion of the body 10 intothe bore 14 is limited by the abutment flange 17 on the body 10 engagingthe workpiece surface 18.

Thereafter, the rod 11 is subjected to repeated impacts by an impacttool or hammer T, shown in broken lines in FIG. 2, while the handle 19is turned to rotate the entire tool in the bore 14. Each blow of thetool T forces the rod 11 downwardly or inwardly against the spring 25,and forces the respective peening arms or elements which are inclined tothe rod 11 outwardly into impact engagement with the bore wall 11, thearms 12 pivoting on the pins 33 and sliding outwardly through theopenings 13. The spring 25 acts to return the peening fingers 12 to theretracted positions, by returning the rod 11 to its upper position,following each downward movement of the rod 11 responsive to impact ofthe tool T with the rod 11.

If the material of the workpiece is so soft that excessive penetrationof the ends 36 of the peening arms or elements into the wall 14 of theworkpiece may occur, the inner end cap 23 may be threadedly adjusted inthe body 10 to limit the permitted stroke of the rod 11. Under theseconditions, the reduced end 26 of the rod 11 will abut the anvil 24,thereby limiting the excursion of the rod 11, and likewise limiting theexcursion of the peening arms or elements 12.

As the peening action continues, the tool is rotated by the handle 19,whereby the ends of the peening elements 12 will effectively contact theentire surface of the bore 14, due to the staggered or spiral relationof the openings 13 through which the ends 36 of the peening arms orelements 12 project.

I claim:

1. In a peening tool for working the wall of a bore in a workpiece:comprising in combination a body, a rod reciprocably carried by saidbody, a plurality of peening arms pivotally mounted on said rod andmovable outwardly relative to said body to engage the bore wall uponmovement of said rod in one direction and retractable by said rod uponmovement of said rod in the other direction, said body comprising atubular sleeve having a plurality of openings through which said peeningarms extend, said openings being circumferentially and axially spaced onsaid tubular sleeve, said rod having an end adapted for engagement by animpact tool to move said rod in said one direction, means for movingsaid rod in said other direction, and means for rotating said body andpeening arms.

2. In a peening tool as defined in claim 1, said peening arms havingarcuate end surfaces for engaging said wall.

3. In a peening tool as defined in claim 1, said means for moving saidrod in said other direction comprising a coil compression springengaging said rod, and said body having a seat for said spring.

4. ln a peening tool as defined in claim 1, an anvil disposed in thepath of movement of said rod in said one direction and contactable bysaid rod, and means adjustably supporting said anvil on said body toadjust the extent of maximum movement of said rod in said one direction.

5. In a peening tool as defined in claim 1, said sleeve including an endcap threadedly mounted thereon, and an anvil in said end cap engageableby said rod to limit movement of said rod in said one direction.

6. In a peening tool as defined in claim 1, said sleeve including an endcap threadedly mounted thereon, an anvil in said end cap engageable bysaid rod to limit movement of said rod in said one direction, and saidmeans for moving said rod in said other direction comprising a coilspring seating on said end cap about said anvil and engaged with saidrod.

7. In a peening tool as defined in claim 1, said sleeve having anabutment flange to limit movement of said body into said bore.

8. In a peening tool as defined in claim 1, said sleeve having anabutment flange to limit movement of said body into said bore, and ahandle on said sleeve for rotating said sleeve in said bore.

9. In a peening tool as defined in claim 1, segmental clamping collarsdisposed about said rod, the segments of said collars having opposingears projecting therefrom, and said peening arms being pivotally mountedbetween and connected to said ears.

10. In a peening tool as defined in claim 1, segmental clamping collarsdisposed about said rod, the segments of said collars having opposingears projecting therefrom said peening arms being pivotally mountedbetween and connected to said ears, said collars having an internalgroove extending circumferentially therein, and said rod having a ribdisposed in said groove.

1. In a peening tool for working the wall of a bore in a workpiece: comprising in combination a body, a rod reciprocably carried by said body, a plurality of peening arms pivotally mounted on said rod and movable outwardly relative to said body to engage the bore wall upon movement of said rod in one direction and retractable by said rod upon movement of said rod in the other direction, said body comprising a tubular sleeve having a plurality of openings through which said peening arms extend, said openings being circumferentially and axially spaced on said tubular sleeve, said rod having an end adapted for engagement by an impact tool to move said rod in said one direction, means for moving said rod in said other direction, and means for rotating said body and peening arms.
 2. In a peening tool as defined in claim 1, said peening arms having arcuate end surfaces for engaging said wall.
 3. In a peening tool as defined in claim 1, said means for moving said rod in said other direction comprising a coil compression spring engaging said rod, and said body having a seat for said spring.
 4. In a peening tool as defined in claim 1, an anvil disposed in the path of movement of said rod in said one direction and contactable by said rod, and means adjustably supporting said anvil on said body to adjust the extent of maximum movement of said rod in said one direction.
 5. In a peening tool as defined in claim 1, said sleeve including an end cap threadedly mounted thereon, and an anvil in said end cap engageable by said rod to limit movement of said rod in said one direction.
 6. In a peening tool as defined in claim 1, said sleeve including an end cap threadedly mounted thereon, an anvil in said end cap engageable by said rod to limit movement of said rod in said one direction, and said means for moving said rod in said other direction comprising a coil spring seating on said end cap about said anvil and engaged with said rod.
 7. In a peening tool as defined in claim 1, said sleeve having an abutment flange to limit movement of said body into said bore.
 8. In a peening tool as defined in claim 1, said sleeve having an abutment flange to limit movement of said body into said bore, and a handle on said sleeve for rotating said sleeve in said bore.
 9. In a peening tool as defined in claim 1, segmental clamping collars disposed about said rod, the segments of said collars having opposing ears projecting therefrom, and said peening arms being pivotally mounted between and connected to said ears.
 10. In a peening tool as defined in claim 1, segmental clamping collars disposed about said rod, the segments of said collars having opposing ears projecting therefrom, said peening arms being pivotally mounted between and connected to said ears, said collars having an internal groove extending circumferentially therein, and said rod having a rib disposed in said groove. 